Polyvalent device for the rapid lifting of sheets of glass

ABSTRACT

A device for lifting sheets of glass brought on a conveyor, has at least one arm rotatable about a horizontal spindle, situated at the lower end of the arm, between a substantially vertical position for gripping the sheets on the conveyor and a substantially horizontal position for depositing the sheets. The device also has a support mounted on the upper end of each rotating arm, the support being slidable along the axis of the arm. The support carries first suction cups for gripping the sheets and at least two retractable arms fastened with the support, the arms being rotatable between a substantially horizontal axis carried by the support, each retractable arm being provided with second suction cups. The retractable arms and the second suction cups are disposed symmetrically with respect to the conveyor axis and in such a way that the sheets of large dimensions are gripped while being in equilibrium.

The invention relates to a device for the rapid lifting of sheets ofglass, said device being adaptable to sheets of varied dimensions(polyvalency).

The sheets of glass are gripped in a substantially horizontal position,for example on a conveyor, and placed in substantially verticalposition, for example stacked on a table. Such operation being calledlifting.

The current lifting machines are designed for specific dimensions ofsheets.

For example, there are lifting machines for sheets of small dimensions(length=600 to 1200 mm, width=400 to 600 mm), working at very rapidrates (one sheet being lifted every 2 secs.) or at more generally rapidrates (3-4 secs).

There are also on the market machines that are designed for sheets ofaverage dimensions (length=1,000 to 1,300 mm, width=1,800 to 3,500 mm)working at slower rates (over 6 secs).

European Patent Application 0 243 236 illustrates a machine for liftingsheets of small dimensions. It comprises arms mounted perpendicularly toa shaft driving them in rotation, gripping means (suction cups) mountedon the end of each arm, said arms being slidable perpendicularly to saidshaft.

To enable financial and installation space savings, the presentinvention proposes a simple and compact lifting machine, capable ofpicking up sheets of variable dimensions, and of working at rapid rates(one sheet being lifted every 4 secs. or more).

More precisely, the device for lifting sheets of glass brought on ahorizontal conveyor, according to the invention, comprises:

at least one arm rotatable about a horizontal axis situated at the lowerend of said arm, between a substantially vertical position for grippingthe sheet and a substantially horizontal position for depositing it,said device further comprising means for rotating the arm,

a support mounted on the upper end of each rotating arm, which supportis slidable along the axis of said arm and carries suction cups forgripping the sheets; the rotating arm or arms, support or supports andsuction cups being disposed symmetrically with respect to the conveyoraxis, their number and position being determined as a function of thedimensions of the sheets to be lifted,

at least two retractable arms fast with the support or supports, whicharms are rotatable between a substantially horizontal working positionand a substantially vertical rest position about a horizontal axiscarried by said support or supports, each arm being provided withsuction cups, said arms and suction cups being disposed symmetricallywith respect to the conveyor axis and in such a way that the sheets oflarge dimensions are gripped while being in equilibrium,

means for synchronously actuating and controlling said retractable arms,support or supports and suction cups.

The invention will be more readily understood from the figures:

FIG. 1 is a lateral view of the device,

FIG. 2 is a plan view of one advantageous embodiment of the deviceaccording to the invention,

FIG. 3 illustrates an advantageous embodiment with nitrogen accumulator.

As illustrated in FIG. 1, the device according to the inventioncomprises at least one arm (1) rotating about the spindle (2) of ahorizontal shaft (3) placed at the lower end of said arm (1).

FIG. 1 only shows one arm, but others may be provided on the samerotation axis and which are not diagrammatically illustrated incross-section.

Rotation is obtained for example by means of a jack (4) operating thespindle (2) of the shaft (3). Other means may also be suitably used foractuating the arm.

The arm or arms move between a substantially vertical position,corresponding to the action of gripping the sheets, and a substantiallyhorizontal position corresponding to the action of depositing thesheets.

At the other end (upper end) of each arm, is provided a support (5)slidable along said arm (1).

Sliding is obtained for example by means of a jack (6) advantageouslyplaced inside said arm (1), thus saving space on the machine.

As illustrated in FIG. 1, the jack (6) is fast with a bearing surface(7) of the support (5) to allow raising or lowering of said support orsupports (5) along the arm. Means are of course provided for operatingthejack (6).

The upper end of each support comprises suction cups (8) or other meansforgripping the sheets of glass. Said suction cups or means may bemounted directly on the support or on fingers fixed on the support.

Means for removing the air from the suction cups or for returning theair therein are provided and, in general, means for actuating saidgripping means.

The device further comprises according to the invention at least tworetractable arms.

FIG. 1 shows one retractable arm (9) which fastens with the support (5).Said arm is rotatable about the horizontal axis (10) of the shaft (11)mounted in the support (5). It is provided with suction cups (12) orothermeans for gripping the sheets.

It can be moved from a horizontal working position to a vertical restposition. The horizontal position corresponds to the action of grippingthe sheets of larger dimensions.

The retracted position corresponds to the action of gripping sheets ofsmall dimensions where only the rotating arm or arms (1) are used.Therefore the suction cups (12) of the retractable arms are notinvolved, only suction cups (8) are working in this case.

Rotation of the retractable arms is caused for example by a jack (13)positioned inside the corresponding assembly constituted of the rotatingarm or arms (1) and support or supports (5).

Retractable arms (9) must be two in number in order for the sheet to belifted in equilibrium.

To that effect also, they are placed symmetrically with respect to theconveyor 20 axis. It is noted that the sheet 22 reaching the grippingstation had been focussed onto the conveyor and that it is in apredetermined and known position making it easier to lift it.

The number of suction cups (12) and their disposition on the retractablearms are likewise selected so that large sheets can be lifted inequilibrium. Such number and disposition are not determinedindependently of the number and position of suction cups (8): they aresuch that each suction cup supports substantially the same surface ofglass.

Quite obviously, the disposition of the retractable arms, their geometryand the disposition of the suction cups are also determined so that theedges of the sheet are supported and the arms can be retracted.

FIG. 2 shows a plan view of a device according to the invention withonly one arm (1), not clearly visible on the figure, with only onesupport (5) covering nearly the whole width of the conveyor is(dimension perpendicular to the conveyor axis, the dimension along theaxis being thelength).

The arm is actuated by the jack (4). Jacks (6) and (13) are shown insidethe arm for actuating the support and the shaft supporting theretractablearms (9).

FIG. 2 shows two arms (9) symmetrically retractable with respect to theconveyor axis, which is also the axis of the single rotating arm. Eacharmsupports suction cups (12).

The suction cups and retractable arms are disposed in such a way thatthe large sheet which is gripped is in equilibrium.

The arms (9) are preferably bent to help their retraction insubstantially vertical position.

The operation of such a device for gripping a large sheet is easilyexplained.

To simplify the explanation, the embodiment comprising only one rotatingarm, two retractable arms and control jacks has been chosen here, butany other embodiments will work in the same way.

A plate is brought on the conveyor to the gripping station.

The rotating arm (1) is vertical so that the active surface of thesuction cups is parallel to the sheet. The retractable arms are broughtto the horizontal position or work position, in parallel to the sheet,by means of jack (13).

The support (5) is lifted by the jack (6) so that the suction cups (8)and (12) in suction condition are in contact with the sheet.

The rotating arm is brought in substantially horizontal position fordepositing the sheet on a table or other means. The suction cups arereleased, and air can even be insufflated into them to help depositingthesheet.

The support (5) is lowered by the jack while the arms (9) are retractedto allow the lifting device to pass under the next sheet already inposition at the gripping station.

According to a more advantageous working method, once the sheet has beengripped, the support (5) is lowered as the rotating arm starts moving.Thesupport (5) is brought forward again for depositing the sheet on thetable or on a mean center. Then the sheet is "thrown" onto the tablewhen air issimultaneously blown by the suction cups.

All these operations are controlled automatically by appropriate meansensuring synchronization of said operations.

For gripping a small sheet, the arms (9) are retracted, only therotating arm or arms (1) and the suction cups (8) are actuated.

With rapid rates, as this is the case with this particular machine,shock effects occur in spite of the fact that accelerations anddecelerations are controlled.

To dampen the movements, a hydraulic jack (4) is advantageously providedfor controlling the rotating arm or arms (1) with a nitrogen accumulator(15) mounted on said jack (4), this device being illustrated in FIG. 3.

The device works as follows. The jack (4) comprises a perforated pistonallowing the oil to flow from one compartment into the other accordingto the movement of the piston rod.

This jack is also connected to the nitrogen accumulator (15) constitutedbya container equipped with a movable wall (16) separating it into twochambers, one (17) is closed and contains the nitrogen, and the other(18)is connected with the jack (4).

The retraction of the rod of jack (4) in order to bring the sheet fromthe gripping station to the depositing station drives the oil towardsthe compartment (18) of the accumulator.

The release of said rod, on the contrary, allows the return of that oil,thus restoring the energy for raising the rotating arm from thedepositingstation back to the gripping station.

Hydraulic jacks (6) and (13) could also be used with nitrogenaccumulators mounted on them.

The principal advantage of such a device is its polyvalency: lifting ofsheets of different dimensions for competitive rates, e.g. up to 2 secs.for small sheets, and more than 4 secs. for larger sheets, coupled witha simplicity of design and implementation.

Preferably, this machine is used for sheets reaching up to 2 m×1.5 m.

I claim:
 1. Device for lifting sheets of glass brought on a conveyor,comprising at least one arm (1) rotatable about a horizontal spindle(2), situated at the lower end of said arm, between a substantiallyvertical position for gripping the sheets on the conveyor and asubstantially horizontal position for depositing said sheets, meansbeing also provided for rotating the arm, device characterized in thatit further comprises:a support (5) mounted on the upper end of eachrotating arm (1), said support (5) being slidable along the axis of saidarm and said support (5) carrying suction cups (8) for gripping thesheets; said rotating arm or arms (1), support or supports (5) andsuction cups (8) being disposed symmetrically with respect to theconveyor axis, their number and disposition being determined as afunction of the dimensions of the sheets to be lifted, at least tworetractable arms (9) which fasten with the support or supports (5) whicharms are rotatable between a substantially horizontal work position anda retracted rest position about a horizontal axis (10) carried by saidsupport or supports (5), each arm (9) being provided with suction cups(12), said arms (9) and suction cups (12) being disposed symmetricallywith respect to the conveyor axis and in such a way that the sheets oflarge dimensions are gripped while being in equilibrium, means forsynchronously actuating and controlling said retractable arms, supportsand suction cups.
 2. Device according to claim 1, characterized in thatsaid means for actuating said retractable arms (9) consist in a jack(13) positioned inside the corresponding assembly constituted of therotating arm (1) and the support (5) and carrying said retractable arms(9), said jack (13) actuating the horizontal axis (10) which transmitsthe movement to said retractable arms (9).
 3. Device according to claim1, characterized in that said device comprises a hydraulic jack (4)actuating a horizontal shaft (3) mounted at the lower end of saidrotating arm or arms (1) and allowing the rotation of said arm or arms(1), and in that it further comprises a nitrogen accumulator (15) at thelevel of said jack (4) to dampen the movements of said rotating arm orarms.
 4. Device according to claim 1, characterized in that hydraulicjacks (6) and (13) actuate the retractable arms (9) and the support orsupports (5), each jack being connected to a nitrogen accumulator (15).